/*
 * Internal interface definitions, etc., for the reg package
 *
 * Copyright (c) 1998, 1999 Henry Spencer.	All rights reserved.
 *
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them.
 *
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 *
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * src/include/regex/regguts.h
 */

/*
 * Environmental customization.  It should not (I hope) be necessary to
 * alter the file you are now reading -- regcustom.h should handle it all,
 * given care here and elsewhere.
 */
#include "regcustom.h"

/*
 * Things that regcustom.h might override.
 */

/* assertions */
#ifndef assert
#ifndef REG_DEBUG
#define NDEBUG /* no assertions */
#endif
#include <assert.h>
#endif

/* voids */
#ifndef DISCARD
#define DISCARD void /* for throwing values away */
#endif
#ifndef VS
#define VS(x) ((void*)(x)) /* cast something to generic ptr */
#endif

/* function-pointer declarator */
#ifndef FUNCPTR
#define FUNCPTR(name, args) (*(name)) args
#endif

/* memory allocation */
#ifndef MALLOC
#define MALLOC(n) selfpalloc(n)
#endif
#ifndef REALLOC
#define REALLOC(p, n) selfrepalloc(VS(p), n)
#endif
#ifndef FREE
#define FREE(p) selfpfree(VS(p))
#endif

/* want size of a char in bits, and max value in bounded quantifiers */
#ifndef CHAR_BIT
#include <limits.h>
#endif
#ifndef _POSIX2_RE_DUP_MAX
#define _POSIX2_RE_DUP_MAX 255 /* normally from <limits.h> */
#endif

/*
 * misc
 */

#define NOTREACHED 0

#define DUPMAX _POSIX2_RE_DUP_MAX
#ifdef INFINITY
#undef INFINITY
#endif
#define INFINITY (DUPMAX + 1)

#define REMAGIC 0xfed7 /* magic number for main struct */

/* Type codes for lookaround constraints */
#define LATYPE_AHEAD_POS 03  /* positive lookahead */
#define LATYPE_AHEAD_NEG 02  /* negative lookahead */
#define LATYPE_BEHIND_POS 01 /* positive lookbehind */
#define LATYPE_BEHIND_NEG 00 /* negative lookbehind */
#define LATYPE_IS_POS(la) ((la)&01)
#define LATYPE_IS_AHEAD(la) ((la)&02)

/*
 * debugging facilities
 */
#ifdef REG_DEBUG
/* FDEBUG does finite-state tracing */
#define FDEBUG(arglist)             \
    {                               \
        if (v->eflags & REG_FTRACE) \
            printf arglist;         \
    }
/* MDEBUG does higher-level tracing */
#define MDEBUG(arglist)             \
    {                               \
        if (v->eflags & REG_MTRACE) \
            printf arglist;         \
    }
#else
#define FDEBUG(arglist) \
    {}
#define MDEBUG(arglist) \
    {}
#endif

/*
 * bitmap manipulation
 */
#define UBITS (CHAR_BIT * sizeof(unsigned))
#define BSET(uv, sn) ((uv)[(sn) / UBITS] |= (unsigned)1 << ((sn) % UBITS))
#define ISBSET(uv, sn) ((uv)[(sn) / UBITS] & ((unsigned)1 << ((sn) % UBITS)))

/*
 * We dissect a chr into byts for colormap table indexing.	Here we define
 * a byt, which will be the same as a byte on most machines...	The exact
 * size of a byt is not critical, but about 8 bits is good, and extraction
 * of 8-bit chunks is sometimes especially fast.
 */
#ifndef BYTBITS
#define BYTBITS 8 /* bits in a byt */
#endif
#define BYTTAB (1 << BYTBITS) /* size of table with one entry per byt value */
#define BYTMASK (BYTTAB - 1)  /* bit mask for byt */
#define NBYTS ((CHRBITS + BYTBITS - 1) / BYTBITS)
/* the definition of GETCOLOR(), below, assumes NBYTS <= 4 */

/*
 * As soon as possible, we map chrs into equivalence classes -- "colors" --
 * which are of much more manageable number.
 */
typedef short color; /* colors of characters */
typedef int pcolor;  /* what color promotes to */


#define MAX_COLOR 32767 /* max color (must fit in 'color' datatype) */
#define COLORLESS (-1) /* impossible color */
#define WHITE 0        /* default color, parent of all others */

/*
 * A colormap is a tree -- more precisely, a DAG -- indexed at each level
 * by a byt of the chr, to map the chr to a color efficiently.	Because
 * lower sections of the tree can be shared, it can exploit the usual
 * sparseness of such a mapping table.	The tree is always NBYTS levels
 * deep (in the past it was shallower during construction but was "filled"
 * to full depth at the end of that); areas that are unaltered as yet point
 * to "fill blocks" which are entirely WHITE in color.
 */

/* the tree itself */
struct colors {
    color ccolor[BYTTAB];
};
struct ptrs {
    union tree* pptr[BYTTAB];
};
union tree {
    struct colors colors;
    struct ptrs ptrs;
};

#define tcolor colors.ccolor
#define tptr ptrs.pptr

/*
 * Per-color data structure for the compile-time color machinery
 *
 * If "sub" is not NOSUB then it is the number of the color's current
 * subcolor, i.e. we are in process of dividing this color (character
 * equivalence class) into two colors.	See src/backend/regex/README for
 * discussion of subcolors.
 *
 * Currently-unused colors have the FREECOL bit set and are linked into a
 * freelist using their "sub" fields, but only if their color numbers are
 * less than colormap.max.	Any array entries beyond "max" are just garbage.
 */
struct colordesc {
    int nschrs;         /* number of simple chars of this color */
    int nuchrs;         /* number of upper map entries of this color */
    color sub;          /* open subcolor, if any; or free-chain ptr */
#define NOSUB COLORLESS /* value of "sub" when no open subcolor */
    struct arc* arcs;   /* chain of all arcs of this color */
    chr firstchr;       /* simple char first assigned to this color */
    int flags;          /* bit values defined next */
#define FREECOL 01      /* currently free */
#define PSEUDO 02       /* pseudocolor, no real chars */
#define UNUSEDCOLOR(cd) ((cd)->flags & FREECOL)
    union tree* block; /* block of solid color, if any */
};

/*
 * The color map itself
 *
 * This struct holds both data used only at compile time, and the chr to
 * color mapping information, used at both compile and run time.  The latter
 * is the bulk of the space, so it's not really worth separating out the
 * compile-only portion.
 *
 * Ideally, the mapping data would just be an array of colors indexed by
 * chr codes; but for large character sets that's impractical.  Fortunately,
 * common characters have smaller codes, so we can use a simple array for chr
 * codes up to MAX_SIMPLE_CHR, and do something more complex for codes above
 * that, without much loss of performance.  The "something more complex" is a
 * 2-D array of color entries, where row indexes correspond to individual chrs
 * or chr ranges that have been mentioned in the regex (with row zero
 * representing all other chrs), and column indexes correspond to different
 * sets of locale-dependent character classes such as "isalpha".  The
 * classbits[k] entry is zero if we do not care about the k'th character class
 * in this regex, and otherwise it is the bit to be OR'd into the column index
 * if the character in question is a member of that class.  We find the color
 * of a high-valued chr by identifying which colormaprange it is in to get
 * the row index (use row zero if it's in none of them), identifying which of
 * the interesting cclasses it's in to get the column index, and then indexing
 * into the 2-D hicolormap array.
 *
 * The colormapranges are required to be nonempty, nonoverlapping, and to
 * appear in increasing chr-value order.
 */

#define NUM_CCLASSES 13 /* must match data in regc_locale.c */

typedef struct colormaprange {
    chr cmin; /* range represents cmin..cmax inclusive */
    chr cmax;
    int rownum; /* row index in hicolormap array (>= 1) */
} colormaprange;

struct colormap {
    int magic;
#define CMMAGIC 0x876
    struct vars *v;       /* for compile error reporting */
    size_t ncds;          /* allocated length of colordescs array */
    size_t max;           /* highest color number currently in use */
    color free;           /* beginning of free chain (if non-0) */
    struct colordesc *cd; /* pointer to array of colordescs */
#define CDEND(cm) (&(cm)->cd[(cm)->max + 1])

    /* mapping data for chrs <= MAX_SIMPLE_CHR: */
    color *locolormap; /* simple array indexed by chr code */

    /* mapping data for chrs > MAX_SIMPLE_CHR: */
    int classbits[NUM_CCLASSES]; /* see comment above */
    int numcmranges;             /* number of colormapranges */
    colormaprange* cmranges;     /* ranges of high chrs */
    color *hicolormap;           /* 2-D array of color entries */
    int maxarrayrows;            /* number of array rows allocated */
    int hiarrayrows;             /* number of array rows in use */
    int hiarraycols;             /* number of array columns (2^N) */

    /* If we need up to NINLINECDS, we store them here to save a malloc */
#define NINLINECDS ((size_t)10)
    struct colordesc cdspace[NINLINECDS];
    union tree tree[NBYTS]; /* tree top, plus lower-level fill blocks */
};

/* fetch color for chr; beware of multiple evaluation of c argument */
#define GETCOLOR(cm, c) ((c) <= MAX_SIMPLE_CHR ? (cm)->locolormap[(c)-CHR_MIN] : pg_reg_getcolor(cm, c))

/*
 * Interface definitions for locale-interface functions in regc_locale.c.
 */

/*
 * Representation of a set of characters.  chrs[] represents individual
 * code points, ranges[] represents ranges in the form min..max inclusive.
 *
 * If the cvec represents a locale-specific character class, eg [[:alpha:]],
 * then the chrs[] and ranges[] arrays contain only members of that class
 * up to MAX_SIMPLE_CHR (inclusive).  cclasscode is set to regc_locale.c's
 * code for the class, rather than being -1 as it is in an ordinary cvec.
 *
 * Note that in cvecs gotten from newcvec() and intended to be freed by
 * freecvec(), both arrays of chrs are after the end of the struct, not
 * separately malloc'd; so chrspace and rangespace are effectively immutable.
 */
struct cvec {
    int nchrs;      /* number of chrs */
    int chrspace;   /* number of chrs allocated in chrs[] */
    chr* chrs;      /* pointer to vector of chrs */
    int nranges;    /* number of ranges (chr pairs) */
    int rangespace; /* number of ranges allocated in ranges[] */
    chr* ranges;    /* pointer to vector of chr pairs */
	int cclasscode; /* value of "enum classes", or -1 */
};

/*
 * definitions for NFA internal representation
 *
 * Having a "from" pointer within each arc may seem redundant, but it
 * saves a lot of hassle.
 */
struct state;

struct arc {
    int type; /* 0 if free, else an NFA arc type code */
    color co;
    struct state* from;        /* where it's from (and contained within) */
    struct state* to;          /* where it's to */
    struct arc* outchain;      /* link in *from's outs chain or free chain */
    struct arc* outchainRev;   /* back-link in *from's outs chain */
#define freechain outchain     /* we do not maintain "freechainRev" */
    struct arc* inchain;       /* link in *to's ins chain */
    struct arc* inchainRev;    /* back-link in *to's ins chain */
    struct arc* colorchain;    /* link in color's arc chain */
    struct arc* colorchainRev; /* back-link in color's arc chain */
};

struct arcbatch { /* for bulk allocation of arcs */
    struct arcbatch* next;
#define ABSIZE 10
    struct arc a[ABSIZE];
};

struct state {
    int no;
#define FREESTATE (-1)
    char flag;           /* marks special states */
    int nins;            /* number of inarcs */
    struct arc* ins;     /* chain of inarcs */
    int nouts;           /* number of outarcs */
    struct arc* outs;    /* chain of outarcs */
    struct arc* free;    /* chain of free arcs */
    struct state* tmp;   /* temporary for traversal algorithms */
    struct state* next;  /* chain for traversing all */
    struct state* prev;  /* back chain */
    struct arcbatch oas; /* first arcbatch, avoid malloc in easy case */
    int noas;            /* number of arcs used in first arcbatch */
};

struct nfa {
    struct state* pre;    /* pre-initial state */
    struct state* init;   /* initial state */
    struct state* final;  /* final state */
    struct state* post;   /* post-final state */
    int nstates;          /* for numbering states */
    struct state* states; /* state-chain header */
    struct state* slast;  /* tail of the chain */
    struct state* free;   /* free list */
    struct colormap* cm;  /* the color map */
    color bos[2];         /* colors, if any, assigned to BOS and BOL */
    color eos[2];         /* colors, if any, assigned to EOS and EOL */
    struct vars* v;       /* simplifies compile error reporting */
    struct nfa* parent;   /* parent NFA, if any */
};

/*
 * definitions for compacted NFA
 *
 * The main space savings in a compacted NFA is from making the arcs as small
 * as possible.  We store only the transition color and next-state number for
 * each arc.  The list of out arcs for each state is an array beginning at
 * cnfa.states[statenumber], and terminated by a dummy carc struct with
 * co == COLORLESS.
 *
 * The non-dummy carc structs are of two types: plain arcs and LACON arcs.
 * Plain arcs just store the transition color number as "co".  LACON arcs
 * store the lookaround constraint number plus cnfa.ncolors as "co".  LACON
 * arcs can be distinguished from plain by testing for co >= cnfa.ncolors.
 */
struct carc {
    color co; /* COLORLESS is list terminator */
    int to;   /* next-state number */
};

struct cnfa {
    int nstates; /* number of states */
    int ncolors; /* number of colors (max color in use + 1) */
    int flags;
#define HASLACONS 01       /* uses lookaround constraints */
    int pre;               /* setup state number */
    int post;              /* teardown state number */
    color bos[2];          /* colors, if any, assigned to BOS and BOL */
    color eos[2];          /* colors, if any, assigned to EOS and EOL */
    char* stflags;         /* vector of per-state flags bytes */
#define CNFA_NOPROGRESS 01 /* flag bit for a no-progress state */
    struct carc** states;  /* vector of pointers to outarc lists */
    /* states[n] are pointers into a single malloc'd array of arcs */
    struct carc* arcs; /* the area for the lists */
};

#define ZAPCNFA(cnfa) ((cnfa).nstates = 0)
#define NULLCNFA(cnfa) ((cnfa).nstates == 0)

/*
 * This symbol limits the transient heap space used by the regex compiler,
 * and thereby also the maximum complexity of NFAs that we'll deal with.
 * Currently we only count NFA states and arcs against this; the other
 * transient data is generally not large enough to notice compared to those.
 * Note that we do not charge anything for the final output data structures
 * (the compacted NFA and the colormap).
 */
#ifndef REG_MAX_COMPILE_SPACE
#define REG_MAX_COMPILE_SPACE (100000 * sizeof(struct state) + 100000 * sizeof(struct arcbatch))
#endif

/*
 * subexpression tree
 *
 * "op" is one of:
 *		'='  plain regex without interesting substructure (implemented as DFA)
 *		'b'  back-reference (has no substructure either)
 *		'('  capture node: captures the match of its single child
 *		'.'  concatenation: matches a match for left, then a match for right
 *		'|'  alternation: matches a match for left or a match for right
 *		'*'  iteration: matches some number of matches of its single child
 *
 * Note: the right child of an alternation must be another alternation or
 * NULL; hence, an N-way branch requires N alternation nodes, not N-1 as you
 * might expect.  This could stand to be changed.  Actually I'd rather see
 * a single alternation node with N children, but that will take revising
 * the representation of struct subre.
 *
 * Note: when a backref is directly quantified, we stick the min/max counts
 * into the backref rather than plastering an iteration node on top.  This is
 * for efficiency: there is no need to search for possible division points.
 */
struct subre {
    char op; /* see type codes above */
    char flags;
#define LONGER 01          /* prefers longer match */
#define SHORTER 02         /* prefers shorter match */
#define MIXED 04           /* mixed preference below */
#define CAP 010            /* capturing parens below */
#define BACKR 020          /* back reference below */
#define INUSE 0100         /* in use in final tree */
#define LOCAL 03           /* bits which may not propagate up */
#define LMIX(f) ((f) << 2) /* LONGER -> MIXED */
#define SMIX(f) ((f) << 1) /* SHORTER -> MIXED */
#define UP(f) (((f) & ~LOCAL) | (LMIX(f) & SMIX(f) & MIXED))
#define MESSY(f) ((f) & (MIXED | CAP | BACKR))
#define PREF(f) ((f)&LOCAL)
#define PREF2(f1, f2) ((PREF(f1) != 0) ? PREF(f1) : PREF(f2))
#define COMBINE(f1, f2) (UP((f1) | (f2)) | PREF2(f1, f2))
    short id;            /* ID of subre (1..ntree-1) */
    int subno;           /* subexpression number (for 'b' and '('), or
                          * LATYPE code for lookaround constraint */
    short min;           /* min repetitions for iteration or backref */
    short max;           /* max repetitions for iteration or backref */
    struct subre* left;  /* left child, if any (also freelist chain) */
    struct subre* right; /* right child, if any */
    struct state* begin; /* outarcs from here... */
    struct state* end;   /* ...ending in inarcs here */
    struct cnfa cnfa;    /* compacted NFA, if any */
    struct subre* chain; /* for bookkeeping and error cleanup */
};

/*
 * table of function pointers for generic manipulation functions
 * A regex_t's re_fns points to one of these.
 */
struct fns {
    void FUNCPTR(pfree, (regex_t*));
    int FUNCPTR(stack_too_deep, (void));
};

#define STACK_TOO_DEEP(re) ((*((struct fns*)(re)->re_fns)->stack_too_deep)())

/*
 * the insides of a regex_t, hidden behind a void *
 */
struct guts {
    int magic;
#define GUTSMAGIC 0xfed9
    int cflags;  /* copy of compile flags */
    long info;   /* copy of re_info */
    size_t nsub; /* copy of re_nsub */
    struct subre* tree;
    struct cnfa search; /* for fast preliminary search */
    int ntree;          /* number of subre's, less one */
    struct colormap cmap;
    int FUNCPTR(compare, (const chr*, const chr*, size_t));
    struct subre* lacons; /* lookaround-constraint vector */
    int nlacons;          /* size of lacons[]; note that only slots
                           * numbered 1 .. nlacons-1 are used */
};

/* prototypes for functions that are exported from regcomp.c to regexec.c */
extern void pg_set_regex_collation(Oid collation);
extern color pg_reg_getcolor(struct colormap * cm, chr c);
